Background

One of the biggest vectors for aquatic invasive species is via the vast amount of ships’ ballast water that is moved around the world annually. It is estimated that there are 7,000 ocean hitchhikers being transported every hour of every day! To tackle this problem the Ballast Water Management Convention has been ratified to enforce water treatment and testing before discharge.

Chelsea Technologies Group, with over 55 years' experience monitoring phytoplankton, were awarded a grant to develop a method for measuring very low concentrations of phytoplankton cells to monitor if ballast water treatment systems are working effectively. As a result, the FastBallast Compliance Monitoring Systems are now capable of determining the phytoplankton cell density of ballast water at the IMO D2 & USCG Discharge Standards (10 to 50 µm range) with a higher degree of confidence than laboratory analysis.

FastBallast is a portable ballast water compliance monitor for use with discrete or flow-through samples. FastBallast’s cutting edge design enables such a rapid and detailed analysis that it is the only technology capable of operating in a flow-through mode, while providing a high degree of accuracy with a representative report on discharge compliance. These easy to use devices are leading the way to effective enforcement of the Convention and will help dramatically reduce the impact of invasive species worldwide.

Users

Users:

Manufacturers of Ballast Water Treatment Systems (BWTS)

Ship yards, operators and owners

Port State Control and other compliance officers

Service suppliers

Analytical Laboratories

Flow-through accessory kit includes pump and precision filtration

Advantages

Sampling issues associated with analysing small static volumes at close to the D2 threshold are overcome by using a larger stirred volume of 20 mLVery low level of false negatives and negligible possibility of false positives

Ballast Water Monitoring

It has long been accepted that ballast water functions as a vector for the transfer of harmful organisms. The IMO ‘Ballast Water Management Convention, 2004’ was established to tackle the problem of invasive species and is being adopted around the world. Ballast water discharge must not contain more than 10 cells/mL of 10 - 50 µm in the smallest dimension. Because this size range is dominated by phytoplankton, active chlorophyll fluorometry is widely viewed as the most appropriate test technology.

The FastBallast active chlorophyll fluorometer provides on board, compliance-level testing, where most systems can only provide indicative results.

Table 1: FastBallast provides an on board compliance-level test

Discrete Sampling - Just Add Water

Pour 20 mL of ballast water into the sample chamber using the measuring cup supplied

Press ‘Run Test’ on the touch pad display

A test takes between 2 and 10 minutes, depending on how close the sample is to the D2 threshold

Size Matters!

Table 2 illustrates how cells of different sizes and species can dramatically affect the results of an indicative test.

With Thalassiosira punctigera (a large diatom), the level 1 (indicative) test generates a false positive (a FAIL result that should have been a PASS). The level 2 (compliance) test correctly assesses the sample as a PASS.

With Dunaliella salina (a small chlorophyte), the level 1 test indicates a cell density below 25% of the microscope-based result. The level 2 test is much closer, at 85% of the microscope-based result.

Figure 1: Distribution based analysis

Figure 1 shows selections from the distribution data (variable fluorescence, Fv) used to generate the level 2 test values in table 2. While both samples report the same Fv, the range of values for Thalassiosira punctigera, as a proportion of the mean value, is clearly many times larger than for Dunaliella salina. This difference arises from the Poisson distribution within the sample and provides the basis of the size-independent distribution method used for level 2 testing by FastBallast.

FastBallast vs. Indicative Test

Table 3: FastBallast's measurement approach.

Indicative tests (level 1) performed with other fluorescence-based systems must assume the amount of fluorescence per cell, which can produce a large error as the fluorescence emitted from cells of different sizes and species varies enormously. The FastBallast level 1 (indicative) test provides a quick indication (within 2 minutes) of whether a sample is grossly compliant or non-compliant. If the level 1 test produces a result between 4% and 4000% of the D2 threshold for a PASS/FAIL, it automatically triggers a level 2 (compliance) test. The FastBallast level 2 test is as accurate as shore based analysis and will always generate a high confidence result.

The Ultimate System

The ultimate system for ballast water discharge analysis

FastBallast provides an ultra-sensitive solution for on board ballast water monitoring at the D2 regulatory limit. High sampling rates, made possible by incorporating Single Turnover Active Fluorometry (STAF), makes FastBallast better suited to analysing phytoplankton cells at the D2 threshold of ten cells/mL than more common (Multiple Turnover) PAM methods.

When analysing a sample, FastBallast first initiates a level 1 indicative test, which takes less than 2 minutes. If this generates a clear PASS or FAIL, testing is halted and the result is reported. If not, FastBallast automatically extends the test to level 2, which is completed in less than 10 minutes.

In contrast to other bulk sample fluorescence methods, the distribution-based FastBallast level 2 test does not require assumptions to be made about the amount of fluorescence per cell. The estimate of cell density generated is within the margin of error for microscope-based analysis up to concentrations of several hundred cells cells/mL.

With FastBallast’s level 2 test, false negatives are extremely unlikely and false positives are virtually impossible. In contrast, estimates of cell density from alternative bulk sample tests can be orders of magnitude away from the true cell density. Consequently, false positive results can only be minimised by setting the threshold for a PASS so low that false negatives become more likely, even at high cell densities.

To allow for potential changes to the regulations, FastBallast also incorporates four excitation wavelengths to provide greater flexibility for interrogating cyanobacteria.

In view of our continual developments, the designs and specifications of our products may vary from those described.

Ocean Hitchhikers

‘Alien species’ describes any species that is not native to that ecosystem, whereas an ‘invasive species’ is a term defined legally in the US as ‘an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health’.

Non-native species are one of the biggest threats to global biodiversity, 2nd only to habitat loss, so considering that we have already entered into ‘the 6th mass extinction on Earth’, this is a serious issue that needs our attention.

One of the largest vectors for marine invasive species is through ships ballast water, where water is used to fill a ship’s ballast tanks in one region and then discharged in another. It’s been estimated that 7,000 species are present within a ship’s ballast water at any one time and depending on a ships trade route, there can easily be over 100 million plankton specimens carried in 1m3 of ballast water (Kabler, 96). So, considering the shipping industry transfers something like 10 billion tonnes of ballast each year, these risks of invasion are tremendous.

Most non-native species do cause harmful ecological effects, and the UK alone is harboring over 2,000 alien species that have become quite happily established. This is a huge problem for global economy as a government assessment has estimated that this is costing the UK economy £1.7 billion annually, and estimates from the US are as high as $137 billion every year!

Prevention is particularly important in the marine environment, where control and eradication become technically challenging – and aquatic species tend to find it easier to become established.

Zebra mussel: Russia to the USA Settled in extremely dense aggregations all over the States, reducing the amount of plankton, blocking internal waterways and threatening 30 species of mussel with extinction.

Downloads

Video: "Invaders From the Sea"Fantastic film giving a unique insight into an important environmental issue: the transfer of harmful organisms in ships' ballast water. This amazing story looks at how this phenomenon is affecting our coasts and millions of lives around the world and the measures taken by the global community to fight against these alien stowaways. Credit: BBC Worldwide-IMO Production. Globallast is a cooperative initiative of the Global Environment Facility, UN Development Programme & IMO. Learn more about the issues around Ballast Water Management - check out the IMO website.

Video: "Protecting the oceans from invasive aquatic species" A key IMO international measure for environmental protection that aims to stop the spread of potentially invasive aquatic species in ships’ ballast water entered into force on 8 September 2017. BWM Convention requires ships to manage their ballast water to remove, render harmless, or avoid the uptake or discharge of aquatic organisms and pathogens within ballast water and sediments.